Fix compile errors with current http-conduit (1.9.2.2)

There were a few changes I had to make:

1. Request no longer has a public constructor, so pattern matching doesn't work
2. insertCookiesIntoRequest is now in Network.HTTP.Conduit.Internal. This may mean it is on it's way out; I don't know.
3. checkStatus now takes 3 arguments; it seemed like the place in Core that it was used, the intention was to ignore all of them, so I added another const.